The ASI's family has been informed about his death, police said.
A Delhi Police assistant sub-inspector allegedly shot himself in the head while on duty at a picket in south Delhi's Kotla Mubarakpur area, officials said on Saturday.
ASI Ramavtar and Sub-Inspector Prem Singh were deployed on night picket duty at BP Marg, an official said.
"At 3 am, Ramavtar informed Prem Singh that he wanted to rest for 10 minutes and went to sit in his car which was parked near the barricade," the official said.
"When Prem Singh went back after sometime, Ramavtar was found dead. He had a bullet injury in his head," the official said, adding that his service revolver was also found lying nearby.
Another official said Ramavtar, a native of Mahendergarh, Haryana, joined the force in 1993 and was currently posted in Kotla Mubarakpur police station.
The ASI's family has been informed about his death, the officer said. The reason behind the "extreme step" is being probed, he added.
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